In the continuing quest for increased storage density in magnetic media storage devices, magnetic thin film heads, such as magnetoresistive (MR) read/write heads or giant magnetoresistive (GMR) read/write heads, have been developed. As opposed to earlier types of magnetic heads, the fabrication of which involves significant piecework and manual handling of individual tiny components, thin film magnetic heads take advantage of semiconductor fabrication processes to form a large number of heads simultaneously on a common substrate or wafer.
In the prior art, sputtered amorphous aluminum oxide was used as a “backfill” material before planarizing thin film head structures. These structures are often several microns thick, requiring hours of time on expensive vacuum sputtering equipment prior to planarization.
Spin-on processes have been used in the fabrication of thin film magnetic heads to planarize and smooth-out pits on the substrate. The use of silicon dioxide, applied as a wet “spin on glass” (SOG), is employed similarly in the semiconductor industry. Spin-on glasses are conventionally heated to temperatures exceeding 300° C. to fully cure and harden the film.
U.S. Pat. No. 5,500,243, issued Mar. 19, 1996 to Danny D. L. Yang discloses a process for forming dielectric thin film coating on a substrate surface, which is suitable for use in magnetic thin film heads. The process of this Prior Art includes the application of a spin-on-glass (SOG) on a substrate, the spinning of the substrate, the preheating of the substrate and thin film to remove the solvents in the spin-on-glass material, and the heating in a reducing or in an inert atmosphere of the film to provide a conversion to a SiO2 film. The preheating step requires a temperature in range from 250° C. and 330° C., and the heating step requires temperature in range from 900° C. and 1100° C. This process only applies for coating a substrate before making magnetic thin film heads. This high temperature processing currently with SOG prevents it from being used later in the process since thin film head structures such as magnetoresistive (MR) and giant magnetoresistive (GMR) sensors are readily damaged by such high temperature.
The process of curing an insulating layer of a thin film head by an electron beam is well known in the prior art. An article titled “Electron Beam Processing of AlliedSignal Accuglass 211 SOG” published in Jun. 16, 1994 by Allied Signal Electron Vision Group teaches an electron beam process, a non-thermal method, for processing spin-on-glass materials. The electron beam process does not require, but may be used in conjunction with, active heating of the substrate and material to achieve the desired cure. However, such processes have not been used in fabrication of MR and GMR heads.
There is a need, therefore, for an improved fabricating process for magnetic thin film heads that is efficient and not operated at high temperatures to overcome the above difficulties.